Obj. 3: Further, who holds the container holds the contents. If, therefore, the New Law is contained in the Old, it follows that whoever had the Old Law had the New: so that it was superfluous to give men a New Law when once they had the Old. Therefore the New Law is not contained in the Old.
On the contrary, As expressed in Ezech. 1:16, there was "a wheel in the midst of a wheel," i.e. "the New Testament within the Old," according to Gregory's exposition.
I answer that, One thing may be contained in another in two ways. First, actually; as a located thing is in a place. Secondly, virtually; as an effect in its cause, or as the complement in that which is incomplete; thus a genus contains its species, and a seed contains the whole tree, virtually. It is in this way that the New Law is contained in the Old: for it has been stated (A. 1) that the New Law is compared to the Old as perfect to imperfect. Hence Chrysostom, expounding Mk. 4:28, "The earth of itself bringeth forth fruit, first the blade, then the ear, afterwards the full corn in the ear," expresses himself as follows: "He brought forth first the blade, i.e. the Law of Nature; then the ear, i.e. the Law of Moses; lastly, the full corn, i.e. the Law of the Gospel." Hence then the New Law is in the Old as the corn in the ear.
Reply Obj. 1: Whatsoever is set down in the New Testament explicitly and openly as a point of faith, is contained in the Old Testament as a matter of belief, but implicitly, under a figure. And accordingly, even as to those things which we are bound to believe, the New Law is contained in the Old.
Reply Obj. 2: The precepts of the New Law are said to be greater than those of the Old Law, in the point of their being set forth explicitly. But as to the substance itself of the precepts of the New Testament, they are all contained in the Old. Hence Augustine says (Contra Faust. xix, 23, 28) that "nearly all Our Lord's admonitions or precepts, where He expressed Himself by saying: 'But I say unto you,' are to be found also in those ancient books. Yet, since they thought that murder was only the slaying of the human body, Our Lord declared to them that every wicked impulse to hurt our brother is to be looked on as a kind of murder." And it is in the point of declarations of this kind that the precepts of the New Law are said to be greater than those of the Old. Nothing, however, prevents the greater from being contained in the lesser virtually; just as a tree is contained in the seed.
Reply Obj. 3: What is set forth implicitly needs to be declared explicitly. Hence after the publishing of the Old Law, a New Law also had to be given. ________________________
FOURTH ARTICLE [I-II, Q. 107, Art. 4]
Whether the New Law Is More Burdensome Than the Old?
Objection 1: It would seem that the New Law is more burdensome than the Old. For Chrysostom (Opus Imp. in Matth., Hom. x [*The work of an unknown author]) say: "The commandments given to Moses are easy to obey: Thou shalt not kill; Thou shalt not commit adultery: but the commandments of Christ are difficult to accomplish, for instance: Thou shalt not give way to anger, or to lust." Therefore the New Law is more burdensome than the Old.
Obj. 2: Further, it is easier to make use of earthly prosperity than to suffer tribulations. But in the Old Testament observance of the Law was followed by temporal prosperity, as may be gathered from Deut. 28:1-14; whereas many kinds of trouble ensue to those who observe the New Law, as stated in 2 Cor. 6:4-10: "Let us exhibit ourselves as the ministers of God, in much patience, in tribulation, in necessities, in distresses," etc. Therefore the New Law is more burdensome than the Old.